This paper presents a numerical study of combustion and multi mode heat transfer in inert porous media. In this case a sintered fiber mat is used. From this work it is understood that the premixed flame is stabilized on the downstream surface of the fiber mat burner. The influence of the flame location, the radiative properties of the porous material, the solid thermal conductivity, and stoichiometry on the flame speed and flame stability are determined using a one-dimensional conduction, convection, radiation, and combustion model. The fiber mat is allowed to emit, absorb, and scatter radiant energy. Non-local thermal equilibrium between the solid and gas was taken into account. Here, separate energy equations for the two phases are introduced, i.e. gas energy equation for the entire system and solid energy equation for the fiber mat. The results indicate that stable combustion can be maintained near the downstream surface of the fiber mat which is mostly controlled by solid-phase radiation.

The mechanism of disk cracking was investigated and an evaluation method for its failure occurrence rate was developed. It was found that the disk cracking was caused by the corrosion pit growth, the superposition of the multiple vibration modes, and the increase in the scatter of the natural frequency due to the interface condition change after long-term operation. The effects of several uncertainties on the failure occurrence rate were examined and the values of the uncertainties were obtained by solving the inverse problem according to the failure analysis; the examined uncertainties were the standard deviation of the natural frequency and the stimulus ratio. It is recommended to perform the replica inspection by removing the blades and to take the proper maintenance actions based on the remaining life evaluations because relatively small corrosion pits can cause crack initiation. It was found that a continuous cover blade is superior to the conventional tenon-shroud-type grouped blade because the former reduces resonance points in the interference diagram and eliminates any tangential modes which are main contributors for the disk cracking.